1. Technical Field
This invention relates to catheters and particularly to a catheter having a twisting lock for drawing the distal end into a predetermined configuration.
2. Description Of Related Art
Suprapubic catheterization of the bladder is used to drain the bladder after surgery or when the genitourinary system is plugged by an obstruction. Other pecutaneously inserted catheters are also used to drain the kidney or biliary system as well as to drain abscesses, other sites of fluid collection and other viscera. Still other pecutaneously inserted catheters are gastrostomy feeding tubes.
These catheters are introduced into the patient by means of a large hypodermic needle or trocar which typically pierces the abdominal wall. A wire guide is inserted through the needle, which is then removed. The catheter tube with a stiffening cannula positioned therein is then passed over the wire guide into the cavity. The cannula and wire guide are withdrawn, leaving the catheter in the desired cavity. With respect to the bladder, the advantage of this technique is that irrigation and infection of the urinary tract is minimized. However, one problem with these catheters is that the catheter can be easily pulled out by movement of the body or by the emptying of, for example, the bladder. Another problem is that side ports at the distal end of the catheter may be inadvertently drawn into the abdominal cavity creating potential for severe infections.
Various catheters have been developed with so-called pigtail loops at their distal ends which both ensures drainage of the cavity and prevents accidental removal therefrom. The pigtail loop is tightened by pulling on the proximal end of a flexible tension member which extends through the catheter. With some catheters, the proximal end of the tension member is held in place by axially placing a hollow cap into or over the proximal end of the catheter tube, thus trapping the flexible tension member of which the protruding end may then be cut.
With other catheters, the flexible tension member is trapped between two or more hollow tubes, one of which is slidably inserted axially into the other. A short length of the flexible member is generally left hanging from the catheter tube so that if the tension member becomes loose, it may be retightened.
In a second generation of this flexible member catheter, an external sleeve is slid over the flexible member protruding from the side of the catheter tube of which the flexible member is then wound around and tied about the sleeve.
Although well suited for its intended purpose, the physician is required to grasp and pull on the flexible tension member and to either secure or tie it about the proximal end of the catheter. Such a flexible tension member left exposed at the proximal end allows the patient to untie the member. As a result, the assistance of hospital personnel is required to retie the member. Furthermore, when the flexible tension member is inadvertently released, the retaining loop at the distal end is released with the possibility of the catheter being withdrawn from the patient.
In another catheter developed by the present inventor and described in U.S. Pat. No. 5,041,085, which is specifically incorporated by reference herein, a sleeve device is utilized to secure the lockable flexible tension member and obtain a fluid tight interconnection. This has the disadvantage of not being adjustable, not allowing for partial locked positions.